<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>CSS盒子模型</title>
    <style>
      body {
        margin: 0;
        padding: 0;
      }
      #box {
        width: 200px;
        height: 200px;
        /* padding: 50px 100px 200px 300px; */
        /* padding: 50px 100px */
        padding: 50px;
        border: 50px solid black;
        margin: 50px;
        background-color: blue;
      }
      #content {
        width: 100%;
        height: 100%;
        background-color: red;
      }
      #outbox {
        width: 200px;
        height: 200px;
        padding: 50px;
        border: 50px solid black;
        /* outline: 50px solid black; */
        margin: 50px;
        background-color: blue;
      }
    </style>
  </head>
  <body>
    <div id="box">
      <div id="content">content</div>
    </div>
    <div id="outbox">outbox</div>
  </body>
</html>
